A term used to describe having sex with someone who is large or has less than desirable physical qualities. It was coined one night when a invitation was sent out to join a party with a "extra large" sorority. When considering to accept said invitation, a man we will simply call JJ calmly said "lets do it, lets tank the whale".

So i went to that girls house the other night and we started to get it on until her room mate walked in and totally saw me tanking the whale.